Racehorses sweat to regulate and lower their body temperature. A horse moderates its temperature when breathing and through the skin. In situations where this is not enough to cool a horse's temperature then it will release heat through sweating.

What does it mean when a horse sweats before a race?

Generally speaking, sweating in racehorses is a good sign insofar as it helps to regulate body temperature. The evaporation of sweat, which is 90% water, creates a cooling effect, known as evaporative cooling, which lowers the body temperature.

Is it good for a horse to sweat?

Like other animals that have sweat glands, horses have sweat glands, too. Sweating is very important for a horse. Sweating is part of a horse's cooling system to relieve heat build-up. A horse can sweat (and should sweat) during exercise; may sweat when it is in pain, under duress, or ill; and may sweat when nervous.